Let’s begin our story in 1961, when Peter Suedfeld was a first-year psychology graduate student at Princeton. Another scholar in the department was running a “sensory deprivation” study that offered $20 to volunteer subjects. Suedfeld wanted the cash, so he agreed to be shut inside a pitch-black, soundproofed room for 24 hours, with only a bit of sustenance and a toilet to keep him company.

He couldn’t handle it. “I was nervous, and I got itchy and jumpy,” he says now. So he left early. He wasn’t the only one. Many subjects panicked, and some even reported they’d had hallucinations.

Though (or perhaps because) he’d gotten spooked, Suedfeld became intrigued by isolation chambers. Sensory deprivation was a sexy field of study in the ’50s and ’60s, and Suedfeld began to organize chamber experiments of his own. Soon enough, he became aware of another isolation technique. A man named John C. Lilly—first at the Naval Institute, later at the National Institute of Mental Health—had pioneered the use of an immersion water tank. In early trials, the subject was completely submerged, wearing a breathing mask, with an air hose connected to a pump. In a later iteration, the subject simply floated in saltwater, on his back, in a coffin-like tank that was completely dark and silent.

Lilly became a cultish, Timothy Leary-like figure as his experiments grew more outlandish. He made attempts to communicate with animals (later dramatized in the Mike Nichols film The Day of the Dolphin) and became famously fond of entering his flotation tanks only after he’d dosed himself with powerful hallucinogens (later dramatized in the Ken Russell film Altered States). Suedfeld met Lilly and was impressed with his tanks—but not his methods. “He started out as a straight scientist,” says Suedfeld. “But he got into taking drugs and thought he’d made contact with some sphere of consciousness beyond the normal. Thought he’d had conversations with Shakespeare and such. We didn’t see eye to eye on how the tanks should be used. I always ran standard experiments with control groups and data and objective tests.”

I had long ago seen Altered States, in which William Hurt devolves into a glowing, primordial beast after he indulges in a little too much tank time. But until I read a trend story about floating in the Wall Street Journal this February, I’d never realized it was possible to float in a non-scientific setting. Nor had it occurred to me that anyone would want to. I was suddenly intrigued: What could sensory deprivation do for me?

There are only a few places to float in New York City. I first tried La Casa, a day spa near Union Square, which features a tank in large part because co-owner Jane Goldberg loves to float.* On a weekday morning, I climbed the stairs to La Casa, took off all my clothes, and, after showering, stepped into a large tub inside an enclosed chamber. I slid the blackout door closed behind me, eased down into the water, and touched a button that switched off the lights. I was floating in total darkness and silence. The saturation of Epsom salts in the water made me unnaturally buoyant—my face, stomach, and knees an archipelago of islands amid the tub’s ocean.

For what must have been the first 15 minutes, I wondered what I was doing there. I thought about my plans for that evening, stories I was working on, whether there was any food in the fridge back at my apartment. I felt bored. I felt silly. Like Peter Suedfeld in that chamber in Princeton, I even got jumpy. I had a brief urge to stand up, water dripping everywhere, and walk out.

Then a transformation began. If you’ve ever taken psychedelic mushrooms (and come on, who hasn’t?) you might recall a certain feeling that arises as the drugs take hold. “Something is happening, something is happening,” your body says to your brain, with mild urgency. I got a feeling akin to that while floating. My brain went a little haywire. When the storm passed, I found myself in a new and unfamiliar state of mind.

* * *

Suedfeld’s studies have, over the years, shown that tank sessions can be used to treat autonomic nervous system problems like chronic pain, high blood pressure, and motion disorders. They can improve perceptual and motor skills in athletes, and creativity in artists. Suedfeld also claims that the tank shifts our brain’s focus from its dominant to its nondominant hemisphere, which has various benefits. “But God only knows why hemisphere balance is affected,” says Suedfeld. “We can’t yet fit a brain scanner in a tank, or get the scanner wet for that matter.”

For a tank newbie like me, not looking to cure physical disorders or win an Olympic medal, the more intriguing aspects of floating include 1) its possibly imagined, Lilly-esque potential to reveal hidden layers of consciousness within, and 2) its proven capacity to chill people out. Suedfeld happily acknowledges point two. “Anything related to psychological stress,” says Suedfeld, “whether it’s chronic tension headaches, insomnia, things with no known physical cause … after several floats, they really seem to improve.”

It’s the meditative, relaxing qualities of floating—even non-hallucinogen-enhanced floating—that eventually moved the practice beyond academia and into retail. Glenn Perry is perhaps the forefather of recreational tank use. Perry was a computer programmer in 1972 when he read Lilly’s book The Center of the Cyclone and, soon after, saw an ad for a Lilly-backed floating workshop. “The first time I floated,” says Perry, “I got out and I found that time had changed and my senses were totally different. I instantly knew I had to build my own tank. By the end of the week, I decided to build tanks not just for myself but for other people. John gave me the name Samadhi—which is a Sanskrit word meaning the state in which a meditator becomes one with the object of meditation.”

After trying out several models, Perry settled on a tank that used 10-inch-deep water saturated with Epsom salts. He and his wife Lee opened a float center in Beverly Hills in 1979, renting out their five tanks largely to entertainment industry types. Michael Crichton came in to float when he had writer’s block. Eventually, Crichton bought a tank of his own.

Between the Perrys’ float center, John Lilly’s 1977 book on the joys of floating titled The Deep Self, and the 1980 release of Altered States, flotation entered the popular consciousness. A November 1981 New York Times trend story was titled “Relaxation Tanks: A Market Develops.” It quoted representatives from Samadhi and other tank companies, noting that the industry was raking in $4 million a year on sales and rentals. It reported that new float centers were opening across the country. It also listed a few notable private tank owners: Robin Williams, Yoko Ono, and the training staffs of the Dallas Cowboys and the Philadelphia Eagles. One happy “tanker” the Times spoke to described the practice as “a self-development kind of thing that allows you to get in tune with yourself.”

In the mid-1980s, the AIDS scare changed everything. People were frightened of contracting HIV from infected water in float tank centers. The business dried up. New Agers switched to yoga. Even the academic work fell out of favor. “Radical students began to equate isolation studies with torture and brainwashing,” says Suedfeld. “People got hassled out of the field.” By the time John Lilly died in 2001, it seemed that floating was over and done.

Turns out it was unsinkable. The February story in the Journal that caught my eye—titled “Float Centers Gaining Steam”—is pretty much a wormhole straight back to that Times trend piece from 30 years before. It notes a new wave of tank enthusiasm, crediting comedian Joe Rogan (a float tankevangelist) and stressed out, chillaxation-hungry Bay Area techies for spreading the word. Further evidence of floating’s resurgence: a float center in Portland, Ore., has inaugurated an annual float conference. Peter Suedfeld—who, after receiving his Ph.D. from Princeton, headed the psychology departments at Rutgers and the University of British Columbia and ran tank studies for years in his own labs—was a featured speaker.

And now I’m part of the movement. Once I’d settled into my first tank session at La Casa, I understood why all these people get jazzed about floating. For the first time in my waking life, I had zero thoughts. It was a mental quietude I’d never known existed.

* * *

“We had a Zen master who visited my lab once,” says Suedfeld, “and he asked to go in the tank for an hour. Most of his life he had meditated every day for four or five hours or more. And he thought the depth of meditation he reached in the tank was on par with a level he reached maybe once a year in his normal meditation environment—which was not exactly the middle of Times Square. He was amazed.”

The water and air in the float chamber are skin temperature, the darkness is identical with eyes open or closed, and there is no sound—thus there is no external input. In turn, my brain decelerated until its output also slowed, and then stopped. I was suspended in a place with no space, or time, or purpose. Once in a while, some quotidian thought would begin to surface at the edges—did I respond to that email?—and then bounce around in the lonely void of my skull for a moment or two. But it would soon melt away as my brain realized it didn’t care. Back to the void.

When my one-hour La Casa session ended with a gentle tapping on the wall—the prearranged signal from the spa—I emerged in a profound daze. I spoke slowly and quietly, like a smooth-jazz DJ, to the person at the spa desk who inquired how my session had gone. I felt more rested than if I’d slept for 16 hours on a pile of tranquilized chinchillas. Outside, colors were saturated; sounds were vivid.

I had to try this again, as soon as possible. For my second session, I went to Blue Light Floatation, on 25th Street in Chelsea. This turned out to be a loft apartment belonging to a tank owner named Sam Zeiger. But the setup was not nearly as weird as you might imagine: Zeiger cordons off a private area in which you float, shower, and change.

Having floated before, my transition happened more quickly this time. It took just a few minutes before I felt my brain and my body slowing, my restless thoughts fading out. If I chose to, I could purposefully focus on one idea at a time, roll it around in isolation, examine some part of my life with no distractions. Or I could just revel in the strangely exhilarating emptiness. At one point, I nodded off in the tank. The only way I knew this was that my limbs lightly spasmed—making a small splash—in that way limbs do when you’re at the edge of sleep. There was no clear line between consciousness and unconsciousness. (I had no fear of drowning, as my buoyancy was such that it would be nearly impossible to roll over accidentally.)

Afterward, as Zeiger handed me a cup of herbal tea, he recounted his own conversion story. “My first time was supposed to be a one-hour session,” he told me, “but the guy forgot about me and left me in the tank for several hours. I had a life-altering experience. I can’t describe it to you now in a way that wouldn’t devalue its meaning.” Zeiger eventually felt compelled to get his own tank and install it in his apartment. Floating in this tank—and maintaining the tank in perfect order, and renting the tank out to other people for $80 an hour—is now his full-time passion.

I went back to La Casa for a final tank session and I knew, as I emerged, that I was hooked. (Disclosure: La Casa gave me my two sessions on the house; Slate paid for the one in Zeiger’s apartment.) This is the closest you will ever come to having a drug-like experience without taking drugs. Though you will have no crazy hallucinations (at least, I didn’t have any—your hallucinatory mileage may vary), you will understand your brain in an entirely new way.

Consider: Right now there are dozens of thoughts pinballing through your mind. When’s lunch? This monitor is too bright. Should I ask her on a second date? My crotch itches. What is the person in the next cubicle saying on the phone? I should be more assertive. I’ll get a burrito at lunch. Am I a good person? These thoughts are all occurring more or less simultaneously. There is a cacophony—a noisy din—in your head. The absence of the din is a genuine revelation. I highly recommend you find that out for yourself.

Peter Suedfeld is now using his accrued wisdom about isolation to consult with NASA and the Canadian Space Agency regarding the effects of long-duration space flight in confined, monotonous environments. Glenn Perry still sells his Samadhi tanks, and says sales are on the rise—you can buy your own starting at about $8,900. The annual float conference is running again this August (motto: “Looking Forward to a Whole Lot More Nothing”).

As for me, I plan to climb back in a tank at least three or four times a year. Just thinking about the feeling I get from floating makes me crave it. I’m not sure I can fully explain why—but I’d love to ponder that question while buoyed by a tub full of warm, salty water.

Correction, May 15, 2013: This article originally misstated the last name of the co-owner of La Casa day spa. She is Jane Goldberg, not Jane Goldman.